Stress affects brain systems involved in risk and reward processing and influences learning and retention of emotionally arousing information. Yet, despite the fact that important decisions and stress often go hand in hand, little is known about the influence of stress on decision processes. This proposal outlines studies to investigate the effect of acute stress on learning and performance in investment tasks for younger and older adults. Stress is likely to have a significant impact on both younger and older adults'decision processes, but the effects may differ for the two groups. Previous research indicates that as people age, they are increasingly likely to prioritize emotion regulation and that this leads to age differences in attention and memory, with older adults showing a positivity (or anti-negativity) effect. Because of this increased focus on affect regulation, older adults are more likely than younger adults to be disproportionately influenced by reward outcomes (rather than loss outcomes) in their decisions. Stress should to amplify (Experiment 1) or diminish (Experiment 2) these age differences, depending on the timing of the stress. In addition, both age and stress should influence decision makers'ability to abandon a no-longer successful strategy and learn a new one (Experiment 3). Understanding the ways in which stress can influence decision processes differently for older and younger adults should promote development of ways to avoid decision biases and errors. Important decisions, such as those regarding personal finances and health care, often involve substantial stress, especially among older adults. The studies in this proposal will provide important information about how stress affects learning and decisions and how those effects may vary with age.